1. Technical Field
The present invention is directed to a system and method for increasing sensitivity of a detection system, and more particularly, to the use of low power microwaves for speeding up reaction kinetics in plasmonic detection systems that include the use of metallic surfaces including metallic films or nanostructures.
2. Background of Related Art
Over the past 10 years, fluorescence has become a dominant technology in medical testing, drug discovery, biotechnology and cellular imaging. The use of fluorescence technology has greatly enhanced the ability to detect specific molecules, leading to rapid advancements in diagnostics. For example, fluorescence detection is widely used in medical testing and glucose analysis because of the high degree of sensitivity obtained using fluorescent techniques.
For example, surface-based assays, in which the amount of target is quantified by capturing it on a solid support and then labeling it with a detectable label, are especially important since they allow for the facile separation of bound and unbound labels. Often detection of binding complexes in array-based assays involves the detection of a fluorescently labeled species that is part of the binding complex. Optical glucose monitoring is one example of an extremely important and active field of research. The goal of this research is to provide a noninvasive method of monitoring and more optimally managing diabetes, a disease that affects millions of people worldwide. A variety of approaches are currently being pursued, including near- and mid-infrared spectroscopy, photoacoustic spectroscopy, polarimetry, diffuse light scattering, and Raman spectroscopy and plasmonic based sensing systems using surface plasmons.
Surface plasmons are electron oscillations on the surface of metals. However, these plasmons are usually non-radiative and difficult to put to practical use. Recently it has been discovered by the present inventors and colleagues that surface plasmons are easily generated and manipulated using the appropriate metal structures, such as metallic nanostructures of appropriate size and shape.
Metal nanostructures have been studied extensively and are emerging as important colorimetric reporters due to their high extinction coefficients, which are typically several orders of magnitude larger than those of organic dyes. In particular, nanostructures made from the noble metals, such as those of silver or gold, with their associated strong plasmon resonance, have generated great interest.
Notably, the close-proximity of metallic silver islands or colloids can alter the radioactive decay rate and/or excitation rate of fluorophores. Further, it has been shown that quantum yield of low quantum yield fluorophores can be increased by proximity to metallic surfaces. The enhanced excitation of fluorophores in close proximity to metallic surfaces including islands, and colloids can have numerous applications in the biochemical and biological applications of fluorescence because of the increased intensity of the fluorescence.
Fluorescence detection is the basis of most assays used in drug discovery and high throughput screening (HTS) today. In all of these assays, assay rapidity and sensitivity is a primary concern. The sensitivity is determined by both the quantum yield of the fluorophores and efficiency of the detection system, while rapidity is determined by the physical and biophysical parameters of temperature, concentration, assay bioaffinity etc.
However, the assays and system discussed hereinabove are limited by the reaction time of the chemical reactions within the assays, such as that which occur in binding or hybridization. Further even with an increase in reaction time, there still may be reduced emissions from the fluorescencing molecule.
Thus, there is a need for detection systems and methods that increase the biological/biochemical kinetics of the reaction without damaging the participating compounds, increase the sensitivity, increase the intensity of emissions from the detection system and that can be used for in both clinical and emergency room assessments.